The present invention relates to a primary drive housing assembly for a motorcycle engine. In a motorcycle engine in which the engine assembly is separate from the transmission assembly, a primary drive assembly is utilized to transfer rotary output from the engine crankshaft to an input shaft of the transmission assembly. The primary drive assembly can include a number of suitable power transmission elements including gearing arrangements, belt and pulley systems, and chain and sprocket systems. In addition to the power transmission elements of the primary drive assembly, many primary drive assemblies include housings that protect and/or support the power transmission elements. The housings may also function to contain oil or other fluids for lubrication of the power transmission elements.
In some instances the primary housing may comprise a relatively large and exposed portion of the motorcycle engine. As such, the aesthetic appearance of the housing may be of some concern. Furthermore, dynamic excitation forces, such as those generated during engine operation, may result in resonance of the primary housing. Such resonance can contribute to undesireable noise during vehicle operation.